added migration order to respect FK dependencies

[motriys98-alt]

Problem

The migration script (migrator.py) migrates tables from SQLite to PostgreSQL in the order returned by sqlite_master, which does not respect foreign key (FK) dependencies.
This causes Foreign Key constraint violations for child tables that reference parent tables not yet migrated:

Child Table	FK Constraint	Missing Parent Key	Rows Lost
chat_file	chat_file_chat_id_fkey → chat(id)	chat_id = '075ec634-...'	33+
chat_message	chat_message_chat_id_fkey → chat(id)	chat_id = 'a2aa8fcf-...'	243+
Total: 276+ rows of data lost due to FK violations during migration.

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Root Cause

The migration loop uses the raw order from sqlite_master:

Old code — order from sqlite_master (arbitrary, ignores FK)

sqlite_cursor.execute("SELECT name FROM sqlite_master WHERE type='table'")
tables = sqlite_cursor.fetchall()

for (table_name,) in tables:
await process_table(table_name, ...)
In the original order, chat was migrated after chat_file and chat_message, causing FK violations.

Solution

1. Add TABLE_MIGRATION_PRIORITY — explicit priority map for all 41 Open WebUI tables. Parent tables get lower numbers (migrated first), child tables get higher numbers.
2. Add resolve_migration_order() — sorts tables by priority before migration.
3. Update migration loop — uses priority-sorted order instead of raw sqlite_master order.

Key priority anchors:

Table	Priority	Role
chat	70	Parent of chat_file, chat_message
chat_file	110	Child — migrated after chat
chat_message	111	Child — migrated after chat

[FedorenkoKirill]

hit exactly this on a real OWUI migration — 3 tables (chat_file, knowledge_file, group_member) landed with 0 rows. Your hardcoded priority map is a straightforward fix; a retry pass over failed tables might be more resilient to future OWUI schema additions